{"product_id":"3-8-thick-5-125-od-round-aluminum-backing-plate-3-through-holes-center-vent-marine-grade-6061-t6","title":"3\/8\" Thick 5.125\" OD Round Aluminum Backing Plate | 3 Through-Holes + Center Vent | Marine Grade 6061-T6","description":"\u003cp style=\"font-size:1.15em;line-height:1.4;margin-bottom:0.75em;text-transform:none;color:#4a7ab5\"\u003e\u003cstrong\u003e5.125\" OD Round Backing Plate with Center Weld Vent\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp style=\"font-weight:400;font-size:0.9em\"\u003ePrecision CNC-machined 6061-T6 aluminum round backing plate with three through-holes and a center vent. Designed as the backside of a sandwich assembly on fiberglass pedestal walls in saltwater marine environments. Three through-holes allow fasteners to pass through and accept nuts on the back side, while the center vent provides weld gas release during installation. Pairs with \u003ca href=\"\/products\/3-8-thick-5-125-od-round-aluminum-countersunk-pad-3-countersunk-holes-center-vent-marine-grade-6061-t6\" style=\"color:#4a7ab5;text-decoration:underline\"\u003eSKU 1012 Countersunk Pad\u003c\/a\u003e for a matching hole pattern. Commonly used on top or through the side of a deck pedestal, as well as through the fiberglass skin of a hardtop or T-top.\u003c\/p\u003e\n\n\u003ctable style=\"font-size:0.9em;border-collapse:collapse\"\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eMaterial\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003eMarine Grade 6061-T6 Aluminum\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eOutside Diameter\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003e5.125\" (130 mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eThickness\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003e3\/8\" (0.375\")\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eThrough-Holes\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003e3 (25\/64\" dia. for 3\/8\" fasteners)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eCenter\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003e1 vent hole (weld gas release)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003ePairs With\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003e\n\u003ca href=\"\/products\/3-8-thick-5-125-od-round-aluminum-countersunk-pad-3-countersunk-holes-center-vent-marine-grade-6061-t6\" style=\"color:#4a7ab5;text-decoration:underline\"\u003eSKU 1012\u003c\/a\u003e (matching CS pad)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eShape\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003eRound\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eFinish\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003eMatte — tumbled, deburred, paint\/powder coat ready\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eWeight\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003e0.7 lb\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003cp style=\"text-transform:none;font-weight:600;font-size:1.05em;color:#4a7ab5\"\u003eCommon Applications\u003c\/p\u003e\n\u003cp style=\"font-weight:400;font-size:0.9em\"\u003eT-tops, tuna towers, hard tops, radar arches, leaning posts, grab bars — commonly used on top or through the side of a deck pedestal, as well as through the fiberglass skin of a hardtop or T-top.\u003c\/p\u003e\n\n\u003cp style=\"text-transform:none;font-weight:600;font-size:1.05em;color:#4a7ab5\"\u003eFrequently Asked Questions\u003c\/p\u003e\n\n\u003cp style=\"font-weight:400;font-size:0.9em\"\u003e\u003cstrong\u003eWhat is a backing plate?\u003c\/strong\u003e\u003cbr\u003e\nA backing plate reinforces the inside of a fiberglass pedestal wall. Fasteners pass through the exterior pad and the pedestal wall, and nuts thread onto the fastener behind the backing plate to lock the assembly in place.\u003c\/p\u003e\n\n\u003cp style=\"font-weight:400;font-size:0.9em\"\u003e\u003cstrong\u003eWhat is the center vent hole for?\u003c\/strong\u003e\u003cbr\u003e\nThe center vent hole allows trapped air and gases to escape during welding, preventing blow-through and ensuring a clean, full-penetration weld.\u003c\/p\u003e\n\n\u003cp style=\"font-weight:400;font-size:0.9em\"\u003e\u003cstrong\u003eDoes this backing plate have a matching countersunk pad?\u003c\/strong\u003e\u003cbr\u003e\nYes — SKU 1010 pairs with SKU 1012, a 3\/8\" thick 5.125\" OD round countersunk pad with the same 3-hole pattern and center vent. The backing plate goes on the inside of the pedestal wall; the countersunk pad goes on the outside for a flush-mount finish.\u003c\/p\u003e\n\n\u003cp style=\"font-weight:400;font-size:0.9em\"\u003e\u003cstrong\u003eWhat size fasteners work with this plate?\u003c\/strong\u003e\u003cbr\u003e\nThe three through-holes are 25\/64\" diameter, sized for 3\/8\" fasteners. Use 3\/8\"-16 stainless hardware with matching nuts for best results.\u003c\/p\u003e\n\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@graph\": [\n    {\n      \"@type\": \"Product\",\n      \"name\": \"3\/8\" Thick 5.125\" OD Round Aluminum Backing Plate | 3 Through-Holes + Center Vent | Marine Grade 6061-T6\",\n      \"sku\": \"1010\",\n      \"mpn\": \"1010\",\n      \"brand\": { \"@type\": \"Brand\", \"name\": \"Welding World\" },\n      \"description\": \"5.125 inch round aluminum backing plate with 3 through-holes and center vent. 3\/8 inch thick, 6061-T6, 25\/64 inch hole diameter for bolted assemblies on fiberglass decks. Pairs with SKU 1012.\",\n      \"material\": \"Aluminum 6061-T6\",\n      \"category\": \"Marine Deck Hardware\",\n      \"offers\": { \"@type\": \"Offer\", \"price\": \"22.00\", \"priceCurrency\": \"USD\", \"availability\": \"https:\/\/schema.org\/InStock\", \"seller\": { \"@type\": \"Organization\", \"name\": \"Welding World\" } }\n    },\n    {\n      \"@type\": \"FAQPage\",\n      \"mainEntity\": [\n        { \"@type\": \"Question\", \"name\": \"What is a backing plate?\", \"acceptedAnswer\": { \"@type\": \"Answer\", \"text\": \"A backing plate reinforces the inside of a fiberglass pedestal wall. Fasteners pass through the exterior pad and the pedestal wall, and nuts thread onto the fastener behind the backing plate to lock the assembly in place.\" } },\n        { \"@type\": \"Question\", \"name\": \"What is the center vent hole for?\", \"acceptedAnswer\": { \"@type\": \"Answer\", \"text\": \"The center vent hole allows trapped air and gases to escape during welding, preventing blow-through and ensuring a clean, full-penetration weld.\" } },\n        { \"@type\": \"Question\", \"name\": \"Does this backing plate have a matching countersunk pad?\", \"acceptedAnswer\": { \"@type\": \"Answer\", \"text\": \"Yes — SKU 1010 pairs with SKU 1012, a 3\/8 inch thick 5.125 inch OD round countersunk pad with the same 3-hole pattern and center vent. The backing plate goes on the inside of the pedestal wall; the countersunk pad goes on the outside for a flush-mount finish.\" } },\n        { \"@type\": \"Question\", \"name\": \"What size fasteners work with this plate?\", \"acceptedAnswer\": { \"@type\": \"Answer\", \"text\": \"The three through-holes are 25\/64 inch diameter, sized for 3\/8 inch fasteners. Use 3\/8-16 stainless hardware with matching nuts for best results.\" } }\n      ]\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"Welding World","offers":[{"title":"Default Title","offer_id":43244276645949,"sku":"Part Number: 1010","price":22.0,"currency_code":"USD","in_stock":false}],"url":"https:\/\/weldingworldinc.com\/products\/3-8-thick-5-125-od-round-aluminum-backing-plate-3-through-holes-center-vent-marine-grade-6061-t6","provider":"Welding World, Inc.","version":"1.0","type":"link"}